1. Field of the Invention
Embodiments of this invention relate to highly active catalysts including molybdenum-containing mixed metal oxides for the production of unsaturated aldehydes from olefins, such as methacrolein, by gas phase catalytic oxidation of isobutylene in the presence of air or another gas containing molecular oxygen.
More particularly, embodiments of this invention relate to highly active catalysts including molybdenum-containing mixed metal oxides for the production of unsaturated aldehydes from olefins, where the molybdenum-containing mixed metal include oxides of (1) molybdenum or molybdenum and tungsten, (2) trivalent metals, (3) divalent metals, (4) monovalent metals and, (5) optionally, other metals that are added as oxides during catalyst preparation. The mixed metal oxides are characterized by having an anion to cation molar (ACM) ratio of ≧1.06 and <2.0 and a divalent to trivalent metal molar ratio between 1.95 and 2.15. The resulting catalyst compositions show an increased relative catalytic activity of at least 2 times compared to mixed metal oxides not having an ACM ratio greater than 1.00 and less than 2.00, and a divalent to trivalent metal molar ratio between 1.95 and 2.15. In other embodiments, when the ingredients at the indicated ratios are combined with a binder such as a silica binder, then the relative catalytic activity is even higher. In other embodiments the ingredients at the indicated ratios are combined with a pore forming agent to produce a different pore distribution in the final catalyst.
2. Description of the Related Art
Many catalysts have been disclosed for use in the production of acrolein or methacrolein by catalytic vapor phase oxidation of propylene or isobutylene. U.S. Pat. No. 4,816,603 discloses a catalyst for production of methacrolein and methacrylic acid of the formula:MoaWbBicFedNieSbfXgYhZiAjOk where X is potassium, rubidium and/or cesium, Y is phosphorus, sulfur, silicon, selenium, germanium and/or boron, Z is zinc and/or lead, A is magnesium, cobalt, manganese and/or tin, a is 12, b is 0.001 to 2, c is 0.01 to 3, d is 0.01 to 8, e is 0.01 to 10, f is 0.01 to 5, g is 0.01 to 2, h is 0 to 5, I is 0.01 to 5, j is 0 to 10 and k is sufficient to satisfy the valences.
U.S. Pat. No. 4,511,671 discloses a catalyst for manufacturing methacrolein of the formula:MoaWbBicFedAeBfCgDhOx where A is at least one of nickel and/or cobalt; B is at least one of alkali metals, alkaline earth metals and/or thallium; C is at least one of phosphorus, tellurium, antimony, tin, cerium, lead, niobium, manganese and/or zinc; D is at least one of silicon, aluminum, zirconium, and/or titanium; a is 12, b is 0 to 10, c is 0.1 to 10, d is 0.1 to 20, e is 2 to 20, f is 0 to 10, g is 0 to 4, h is 0 to 30 and x is determined by the atomic valences.
U.S. Pat. No. 4,556,731 discloses a catalyst for production of methacrolein and methacrylic acid of the formula:AaBbFecXdMeMo12Ox where A is an alkali metal, such as potassium, rubidium, cesium or mixtures thereof, thallium, silver or mixtures thereof, B is cobalt, nickel, zinc, cadmium, beryllium, calcium, strontium, barium, radium or mixtures thereof, X is bismuth, tellurium or mixtures thereof and M is (1) Cr+W, Ge+W, Mn+Sb, Cr+P, Ge+P, Cu+W, Cu+Sn, Mn+Cr, Pr+W, Ce+W, Sn+Mn, Mn+Ge or combinations thereof, (2) Cr, Sb, Ce, Pn, Ge, B, Sn, Cu or combinations thereof, or (3) Mg+P, Mg+Cu, Mg+Cr, Mg+Cr+W, Mg+W, Mg+Sn or combinations thereof, a is 0 to 5, b is 0 to 20, c is 0 to 20, d is 0 to 20, e is 0.01 to 12 and x satisfies the valence requirements.
U.S. Pat. No. 5,245,083 discloses a catalyst for preparing methacrolein of a mixture of composition (1) of the formula:MoaBibFecXdZfOg where X is Ni and/or Co, Z is at least one of W, Be, Mg, S, Ca, Sr, Ba, Te, Se, Ce, Ge, Mn, Zn, Cr, Ag, Sb, Pb, As, B, P, Nb, Cu, Cd, Sn, Al, Zr and Ti, a is 12 b is 0.1 to 10, c is 0 to 20, d is 0 to 20, f is 0 to 4 and g satisfies the valence requirement and composition (2) of the formula:AmMonOp where A is at least one of K, Rb and Cs, m is 2, n is 1 to 9 and p is 3n+1.
U.S. Pat. No. 5,138,100 discloses a catalyst for preparing methacrolein with a mixture of composition (1) of the formula:MoaBibFecXdYeZfOg where X is at least one of Ni and Co, Y is at least one of K, Rb, Cs and Ti, Z is at least one of the elements belonging to Groups 2, 3, 4, 5, 6, 7, 11, 12, 13, 14, 15 and 16, specifically beryllium, magnesium, calcium, strontium, barium, titanium, zirconium, cerium, niobium, chromium, tungsten, manganese, copper, silver, zinc, cadmium, boron, aluminum, germanium, tin, lead, phosphorus, arsenic, antimony, sulfur, selenium and tellurium, a is 12, b is 0.1 to 10, c is 0 to 20, d is 0 to 20, e is 0 to 2, f is 0 to 4, and g satisfies the valence requirement and composition (2) of the formula:LnhMoiOj where Ln is at least one of the rare earth elements, h is 0.2 to 1.5, I is 1 and j satisfies the valence requirement. The atomic ratio of the rare earth element to molybdenum is disclosed to be in the range from 0.2 to 1.5 with an atomic ratio less than 0.2 resulting in high selectivity but poor activity and with an atomic ratio greater than 1.5 resulting in high activity but poor selectivity.
U.S. Pat. No. 4,537,874 discloses a catalyst for production of unsaturated aldehydes of the formula:BiaWbFecModAeBfCgDhOx where A is nickel and/or cobalt, B is at least one of alkali metal, alkaline earth metals and thallium, C is at least one of phosphorus, arsenic, boron, antimony, tin, cerium, lead and niobium, D is at least one of silicon, aluminum, zirconium and titanium, a is 0.1 to 10.0, b is 0.5 to 10.0, c is 0.1 to 10.0, d is 12, e is 2.0 to 20.0, f is 0.001 to 10.0, g is 0 to 10.0 and h satisfies the valence requirement. The ratio of a/b is 0.01 to 6.0 so that bismuth is combined very stably with tungsten and compounds such as bismuth trioxide and bismuth molybdate are not formed.
U.S. Pat. No. 5,728,894 discloses a catalyst for producing methacrolein of the formula:Mo12BiaCebKcFedAeBfOg where A is Co or a mixture of Co and Mg having an atomic ratio of Mg to Co not more than 0.7, B is Rb, Cs or a mixture thereof, a is 0 to 8, b is 0 to 8, c is 0 to 1.2, d is 0 to 2.5, e is 1.0 to 12, f is 0 to 2.0, g satisfies the valence requirement. The relative atomic ratio of iron to bismuth and cerium should be 0<d/(a+b+d)≦0.9. The relative atomic ratio of bismuth, cerium and potassium should be 0.05≦b/(a+b+c)≦0.7. The relative atomic ratio of potassium to bismuth and cerium should be 0<c/(a+b+c)≦0.4. Bismuth, cerium, potassium, iron and cobalt are indispensable elements for the disclosed invention.
U.S. Pat. No. 5,166,119 discloses a method for preparing a catalyst of molybdenum, bismuth, iron and cesium or thallium for producing methacrolein and methacrylic acid by gas phase catalytic oxidation of isobutylene or tert-butanol with molecular oxygen. There is no preference disclosed of cesium over thallium.
U.S. Pat. No. 6,946,422 discloses a process for making a catalyst containing oxides of molybdenum, bismuth, iron, cesium and, optionally, other metals, such as tungsten, cobalt, nickel, antimony, magnesium, zinc, phosphorus, potassium, rubidium, thallium, manganese, barium, chromium, boron, sulfur, silicon, aluminum, titanium, cerium, tellurium, tin, vanadium, zirconium, lead, cadmium, copper and niobium wherein metal compounds are dissolved and then precipitated as a catalyst precursor which is calcined to form a mixed metal oxide catalyst. The process of the present invention uses an organic acid, such as acetic acid, instead of nitric acid to dissolve the bismuth compound and, optionally, other metal compounds. The catalyst synthesized by this process may be used for the production of unsaturated aldehydes, such as methacrolein, by gas phase catalytic oxidation of olefins, such as isobutylene.
U.S. Pat. No. 7,229,945 disclosed a process for making a catalyst for production of unsaturated aldehydes, such as methacrolein, by gas phase catalytic oxidation of olefins, such as isobutylene, said catalyst containing oxides of molybdenum, bismuth, iron, cesium, tungsten, cobalt, nickel, antimony, magnesium and zinc. The process is a two-part synthesis of the catalyst with the water insoluble components in one part and the water soluble components in the other part. The water insoluble components are co-precipitated to form an intermediate catalyst precursor of a precipitated support incorporating oxides of the metal components. The intermediate catalyst precursor is filtered and washed to remove nitrates. The intermediate catalyst precursor is slurried with the remaining water soluble components. A final catalyst precursor is formed by removing the water and incorporating the water soluble components. This two-part process reduces the amount of nitrates in the final catalyst precursor.
U.S. Pat. No. 7,232,788 disclosed a catalyst for production of unsaturated aldehydes, such as methacrolein, by gas phase catalytic oxidation of olefins, such as isobutylene, contains oxides of molybdenum, bismuth, iron, cesium and, optionally, other metals. The catalyst has a certain relative amount ratio of cesium to bismuth, a certain relative amount ratio of iron to bismuth and a certain relative amount ratio of bismuth, iron, cesium and certain other metals to molybdenum and, optionally, tungsten. For a catalyst of the formula:Mo12BiaWbFecCodNieSbfCsgMghZniPjOx wherein a is 0.1 to 1.5, b is 0 to 4, c is 0.2 to 5.0, d is 0 to 9, e is 0 to 9, f is 0 to 2.0, g is from 0.4 to 1.5, h is 0 to 1.5, I is 0 to 2.0, j is 0 to 0.5 and x is determined by the valences of the other components, c:g=3.3 5.0, c:a=2.0 6.0 and (3a+3c+2d+2e+g+2h+2i)/(2×12+2b)=0.95 1.10.
U.S. Pat. No. 7,361,791 disclosed a catalyst for production of unsaturated aldehydes, such as methacrolein, by gas phase catalytic oxidation of olefins, such as isobutylene, contains oxides of molybdenum, bismuth, iron, cesium and, optionally, other metals. The catalyst has a certain relative amount ratio of cesium to bismuth, a certain relative amount ratio of iron to bismuth and a certain relative amount ratio of bismuth, iron, cesium and certain other metals to molybdenum and, optionally, tungsten. For a catalyst of the formula:Mo12BiaWbFecCodNieSbfCsgMghZniPjOx wherein a is 0.1 to 1.5, b is 0 to 4, c is 0.2 to 5.0, d is 0 to 9, e is 0 to 9, f is 0 to 2.0, g is from 0.4 to 1.5, h is 0 to 1.5, I is 0 to 2.0, j is 0 to 0.5 and x is determined by the valences of the other components, c:g=3.3-5.0, c:a=2.0-6.0 and (3a+3c+2d+2e+g+2h+2i)/(2×12+2b)=0.95-1.10.
U.S. Pat. No. 7,494,952 disclosed a process for making a catalyst for production of unsaturated aldehydes, such as methacrolein, by gas phase catalytic oxidation of olefins, such as isobutylene, said catalyst containing oxides of molybdenum, bismuth, iron, cesium, tungsten, cobalt, nickel, antimony, magnesium and zinc. The process is a synthesis of the catalyst with aging or digestion of the reaction slurry with little or no agitation. A catalyst precursor is formed from the water insoluble and water soluble components and is dried. The metal oxide catalyst is formed by calcination of the catalyst precursor.
U.S. Pat. No. 7,501,377 disclosed a catalyst for production of unsaturated aldehydes, such as methacrolein, by gas phase catalytic oxidation of olefins, such as isobutylene, contains oxides of molybdenum, bismuth, iron, cesium and, optionally, other metals. The catalyst has a certain relative amount ratio of cesium to bismuth, a certain relative amount ratio of iron to bismuth and a certain relative amount ratio of bismuth, iron, cesium and certain other metals to molybdenum and, optionally, tungsten. For a catalyst of the formula:Mo12BiaWbFecCodNieSbfCsgMghZniPjOx wherein a is 0.1 to 1.5, b is 0 to 4, c is 0.2 to 5.0, d is 0 to 9, e is 0 to 9, f is 0 to 2.0, g is from 0.4 to 1.5, h is 0 to 1.5, I is 0 to 2.0, j is 0 to 0.5 and x is determined by the valences of the other components, c:g=3.3-5.0, c:a=2.0-6.0 and (3a+3c+2d+2e+g+2h+2i)/(2×12+2b)=0.95-1.10.
The prior art disclosed mixed metal oxide catalysts, which contain molybdenum, bismuth, iron, nickel, cobalt, cesium and other metals for the production of methacrolein. Furthermore, the prior art disclosed certain ranges of amounts of these metals. Some of the prior art disclosed relative ratios of certain components to other components. The effect of the selection of certain components for a mixed metal oxide catalyst compositions for the production of methacrolein and the relative relationship of some of these components to other components has not been investigated in complete detail. However, there is still an need in the art for mixed metal oxidation catalyst compositions, for the production of unsaturated aldehydes, having enhanced relative catalytic activity due to the addition of an amount of molybdenum above an anion to cation molar ratio of 1.0, where the amount is sufficient to ensure that all or substantially all divalent metals are converted to molybdate phases, where the increased molybdate-divalent metal oxide phases correlate with enhanced relative catalytic activity of the catalyst compositions of this invention compared to catalyst compositions not including the additional molybdenum.